SOLUTION: A swimmer aims his body North directly across a 80 m river at a velocity of 1.2 m/s. If the river is moving West at 0.7 m/s, (a) how far downstream will he land and (b) how long wi

Algebra ->  Vectors -> SOLUTION: A swimmer aims his body North directly across a 80 m river at a velocity of 1.2 m/s. If the river is moving West at 0.7 m/s, (a) how far downstream will he land and (b) how long wi      Log On


   



Question 1173878: A swimmer aims his body North directly across a 80 m river at a velocity of 1.2 m/s. If the river is moving West at 0.7 m/s, (a) how far downstream will he land and (b) how long will it take him to cross the river?
Found 2 solutions by Alan3354, ikleyn:
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
A swimmer aims his body North directly across a 80 m river at a velocity of 1.2 m/s. If the river is moving West at 0.7 m/s, (a) how far downstream will he land and (b) how long will it take him to cross the river?
-----------------------
Assuming "aims his body north" means he swims facing North:
========================
If the river is moving West at 0.7 m/s
---------
Currents and wind are given as the direction they're from.
-----
It's a vector problem with a right triangle.
His speed is the hypotenuse with sides of 1.2 and 0.7
c^2 = 1.2^2 + 0.7^2
======================
Time to cross = 80/c = t
-----------------
Distance downstream = 0.7*t

Answer by ikleyn(52835) About Me  (Show Source):
You can put this solution on YOUR website!
.

In precise terms of Physics,  this passage   "A swimmer aims his body North directly across a river"

means that his velocity relative to the river's flow is directed North.